In mining it is conventional to use a ball joint to connect the prop head of a hydraulic prop and the shield canopy of a shield-type support frame, for instance, a so-called shield support. In known shield-supports, use is made of a prop head bearing which forms the socket, wherein the securing element is mounted so as to be pivotably around a swivel axis. A movable locking bolt, releasably connected to the prop head receiving portion, extends parallel to and at a distance from the swivel axis. When in the secured position, the side of the securing element remote from the prop head of the hydraulic prop abuts the locking bolt, so that the securing element cannot accidentally be twisted out of the secured position.
GB 2 098 255 A discloses a mechanical connection device between head or foot of a prop and the canopy or base of roof supports. The device disclosed therein comprises a pivot pin which extends trough the head of the prop and has at each end a flat which is adapted to bear against a plane surface of a holding member integral with a canopy or base. The pivot pin is locked by means of two stirrups fixed by pin elements in holes to the holding member.
Further, U.S. Pat. No. 7,201,541 B2 discloses a prop head bearing between the roof bar and the prop of a shield-type support frame, comprising a ball-joint socket on the roof bar and opened towards the prop for receiving a ball-joint head on the prop, with at least one movable securing pin. When in a secured position, the securing pin engages in a recess in the joint head to prevent accidental lifting of the joint head out of the socket, and with a locking pin which locks the securing pin in the secured position.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.